You plan to build a cylindrical container with no top. The material used for the lateral sides costs $4 per square foot while the material for the bottom costs $5 per square foot.
a) Express the total cost of building the cylinder, C in terms of the cylinder's radius, r, and height, h.
C= ___________
b) If the volume of the cylindrical container is 250 cubic feet, express the total cost of building the cylinder, C in terms of the cylinder's radius, r.
C(r)=__________